This invention relates to an automatic weighing, filling and packing device and, especially, to a rotary weighing, filling and packing machine comprising a rotary table or turret provided with a plurality of weighing heads arranged circularly thereon for automatically and successively effecting such operations as filling, weighing and packing product at respective fixed locations disposed around it.
British Pat. No. 1,013,130 discloses an example of such machine according to the prior art. It includes a turret provided with a plurality of weighing heads each having a weigh hopper or bucket. A plurality of operating locations are disposed along the periphery of the turret and specific operations are applied to each weighing head when it passes these locations. In the cited example, for instance, a predetermined amount of product is fed to the weighing hopper by an automatic feeder at the first location and a container is fed and filled with the product discharged from the weigh hopper at the last location. At the locations between both locations, the product in the weigh hopper is weighed for generating a weight signal and, based upon this weight signal, judgement of acceptability of the packed product and adjustment of the amount of product to be fed are effected.
Although this type of automatic weighing and packing machine is effective when the product is hard and/or has a relatively large grain size and accompanied by no dust, part of product may remain in the weigh hopper to cause an error in the net weight of the packed product when the product is powdered or viscous and, especially, sticky. In order to solve this problem, one may use such a method as weighing product after filling the container. More particularly, consideration has been given to substituting for each weigh hopper a weighing cradle onto which a container may be placed and filled with product, as suggested in the British patent publication No. 2,195,779A. However, this system is undesirable when the container has an unstable shape as in the case of a soft bag.